The results have indicated abundant diversity among South American species and limited variation in North American pumas, tigers, and previously documented bottlenecked cheetahs, pumas and lions. A phylogenetic analysis of Zfx versus Zfy intron and coding sequences demonstrated two examples of ectopic gene conversion within the felid radiations affirming its role in editing functional Y chromosome genes. Concordant phylogenetic and phylogeographic studies of feline immunodeficiency virus transmission among free-ranging cat populations allows a glimpse of the process of emerging infections in species well suited for discovery of these events. Insight gained from these studies reveals evolved mechanisms for immune and natural defenses against fatal infections and neoplastic diseases. Animal Models for AIDS - AIDS, FIV, Phylogenetics, population genetics, - Neither Human Subjects nor Human Tissues